Problem Note 4820: Alpha VMS incorrectly produces negative zero result
On Alpha VMS, a negative zero value may be generated when the user
expects a zero result. The negative zero value is not equivalent to
zero. This behavior may produce incorrect results when doing a
comparison to zero.
The following sample code demonstrates the problem. In the data set
B, 0*(-1) should return a result of zero, and the subsequent MERGE
should produce one observation. On Alpha VMS, the MERGE produces two
observations because the result 0*(-1) is negative zero.
DATA A;
X=0;
RUN;
DATA B;
X=0*(-1);
RUN;
DATA C;
MERGE A B;
BY X;
RUN;
A circumvention is to specify the system option NOCODEGEN for any job
that encounters the problem.
A Technical Support hot fix for Release 8.1 TSLEVEL TS1M0 for this
issue is available at:
http://www.sas.com/techsup/download/hotfix/81_sbcs_prod_list.html#004820
A Technical Support hot fix for Release 8.2 TSLEVEL TS2M0 for this
issue is available at:
http://www.sas.com/techsup/download/hotfix/82_sbcs_prod_list.html#004820
For customers running SAS with Asian Language Support (DBCS), this
hot fix should be downloaded from:
http://www.sas.com/techsup/download/hotfix/82_dbcs_prod_list.html#004820
Operating System and Release Information
| SAS System | Base SAS | OpenVMS Alpha | 8 TS M0 | 9 TS M0 |
*
For software releases that are not yet generally available, the Fixed
Release is the software release in which the problem is planned to be
fixed.
| Type: | Problem Note |
| Priority: | high |
| Date Modified: | 2002-04-25 15:03:40 |
| Date Created: | 2001-04-25 09:23:32 |
